Title : THE ADDED MASS AND DAMPING OF TWO CYLINDERS OSCILLATING IN LIQUID HELIUM II

Corporate Author : ARMY RESEARCH OFFICE DURHAM N C

Personal Author(s) : REYNOLDS,J.M. ; HUSSEY,R.G.

Report Date : MAR 1962

Pagination or Media Count : 1

Abstract : The added mass and damping of two circular cylinders oscillating in liquid helium II were observed with a torsion pendulum and compared with a viscous fluid theory due to Stokes. The cylinders were Lucite rods (.32 cm radius) constrained to move with their axes parallel to and equidistant from the axis of rotation by means of Lucite end plates. The effect of a rigid cylindrical boundary on the added mass is given by a boundary factor F, the principal terms of which are: 2 2 2 4 r 8r a b 1 1 F = 1 - + 2 4 4 2 2a (b - a ) where r sub 1 = radius of each cylinder, a = distance of each cylinder's axis from axis of rotation and b = radius of boundary. In the experiment, a/r sub 1 5 and 8.6 < b/r sub 1 < 11. The range of the experiment is given by: .03 < penetration depth/r sub 1 < .6 and .02 < amplitude/r sub 1 < 0.62. Both the logarithmic decrement and the added moment of inertia are independent of amplitude. The observed logarithmic decrement is in agreement with theory. End effects reduce the added moment of inertia as much as 2% below predicted values. (Author)